Method for producing mineral wool

Abstract

PCT No. PCT/EP92/01914 Sec. 371 Date Jul. 20, 1994 Sec. 102(e) Date Jul. 20, 1995 PCT Filed Aug. 20, 1992 PCT Pub. No. WO94/04468 PCT Pub. Date Mar. 3, 1994A method for producing mineral wool of a material which is highly fluid at an elevated liquidus temperature in particular above 1,200 DEG C., with a viscosity of less than 5,000 poises at liquidus temperature, is proposed wherein the molten mineral material, after having destroyed all nuclei of crystallization, is supplied into a spinner (1') the peripheral wall (19) of which comprises a multiplicity of orifices with small diameters wherethrough said molten material is centrifuged to form filaments which, in a given case, are subjected to a supplementary attenuating effect of a preferably hot gas flow flowing along said peripheral wall (19) of said spinner (1') and generated by a concentric annular external burner (13). If fiberization of such a material is effected in the traditional way, a great proportion of unfiberized particles in the product will result. To avoid this, the spinner temperature in ongoing, continuous operation is maintained at a balanced value which is lower than or equal to the temperature at which the viscosity of the molten mineral material is 100 poises, and higher than the crystallization temperature in undercooled state of said material to be fiberized.

We claim: 
     
       1. A method for producing mineral wool, comprising: providing a material having a liquidus temperature above 1200° C. and a viscosity of less than 5000 poises at said liquidus temperature;   melting said material;   heat treating said molten material for a treatment period sufficient to destroy all nuclei of crystallization;   introducing the molten material into a spinner having a peripheral wall that comprises a plurality of orifices;   centrifuging the molten material through said plurality of orifices thereby forming a plurality of filaments;   attenuating said plurality of filaments by subjecting said plurality of filaments to a heated gas flow flowing along said peripheral wall, said heated gas flow being heated by an annular external burner concentrically disposed with respect to said spinner; and   maintaining a spinner temperature during ongoing operation of said spinner so that said spinner temperature is lower than or equal to a temperature at which the viscosity of the molten material is 100 poises, and higher than a crystallization temperature in an undercooled state of the molten material.   
     
     
       2. The method of claim 1, wherein said treating step comprises: maintaining the molten material at a temperature higher than or equal to an upper temperature of devitrification T SD  of the molten material for at least 30 minutes.   
     
     
       3. The method of claims 1 or 2, wherein said crystallization temperature in an undercooled state of the molten material is stabilized so that said crystallization temperature in an undercooled state does not depend upon a duration of said treatment period. 
     
     
       4. The method of claim 4, wherein said spinner temperature is maintained in part through heating means disposed within said spinner. 
     
     
       5. The method of claim 1, wherein said heating means comprises a diverging internal annular burner. 
     
     
       6. The method of claim 5, wherein said diverging internal annular burner generates flames proximate to an inner surface of said peripheral wall of said spinner. 
     
     
       7. The method of claim 6, further comprising: retaining said flames proximate to said inner surface of said peripheral wall of said spinner by flame retention means disposed at an inner surface of a tulip-shaped skin of said spinner.   
     
     
       8. The method of claim 1, wherein said annular external burner is disposed approximately 15 to 20 mm from an upper side of said peripheral wall of said spinner. 
     
     
       9. The method of claim 1, wherein said annular external burner comprises an inner wall and an outer wall, said inner wall and said outer wall defining a discharge channel for emission of said heated gas flow, wherein a diameter of said inner wall is smaller than a diameter of an upper side of said peripheral wall of said spinner. 
     
     
       10. The method of claim 1, wherein said annular external burner comprises channel wall defining a discharge channel, each of said channel walls including an oblique surface, thereby forming a flaring discharge orifice for said heated gas flow. 
     
     
       11. The method of any one of claims 8 to 10, further comprising: preventing said gas flow from back-flowing away from said peripheral wall by sealing means.   
     
     
       12. The method of claim 1, wherein said spinner temperature is maintained in part through an annular induction heater. 
     
     
       13. The method of claim 1, further comprising: feeding the molten material to a distributing means, said distributing means comprising a bottom wall and a protective plate of heat resistant insulating material.   
     
     
       14. The method of claim 1, wherein said spinner is configured to avoid zones where the molten material stagnates. 
     
     
       15. The method of claim 1, wherein said spinner comprises a cobalt-based alloy reinforced with carbides. 
     
     
       16. The method of claim 1, wherein said spinner comprises a nickel-based alloy with gamma prime reinforcement. 
     
     
       17. The method of claim 1, wherein said spinner comprises a ceramic material. 
     
     
       18. The method of claim 17, wherein said ceramic material comprises silicon nitride. 
     
     
       19. The method of claim 17, wherein said ceramic material comprises silicon carbide. 
     
     
       20. The method of claim 1, wherein said spinner comprises an oxide dispersion strengthened (ODS) alloy. 
     
     
       21. The method of claim 20, wherein said ODS alloy has the following composition: Cr 13 to 30% wt.   Al 2 to 7% wt.   Ti less than 1% wt.   Y 2  O 3  0.2 to 1% wt.   Fe remainder.   
     
     
       22. The method of claim 20, wherein said ODS alloy has the following composition: Cr 15 to 35% wt.   C 0 to 1% wt.   Al 0 to 2% wt.   Ti 0 to 3% wt.   Fe less than 2% wt.   Y 2  O 3  0.2 to 1% wt.   Ni remainder.